The present invention relates to the field of patient supports, more particularly to an adjustable chair for use in dental operatories and other medical examination rooms.
There are three principal attributes which must be addressed in the design of a patient support, particularly one that is used in a dental operatory, namely, aesthetic appeal, functionality, and economy. Aesthetics are particularly important in the dental operatory setting, where the patients remain clothed while being treated. This requires a more plush environment than a standard clinical examination room, for the psychological comfort of the patient. The dental operatory must, therefore, maintain the appearance of a warm room with furniture, rather than that of a cold examination room. The patient support must appear to be stylish, comfortable, and modern in order to calm the patient and to enhance the professional appearance of the dentist.
Functionality in a patient support entails its being easily adjustable, in order to orient the area being worked on at an optimum position for the work being done. It must be sturdy enough to support a variety of body sizes and shapes while remaining comfortable and adjustable for all patients. The patient support must be easy to enter and exit. Another characteristic of a desirable patient support is its ride, the sensation experienced by a patient while the chair is being reclined to an operating position and returned to a fully upright position. The ride must be smooth and should preferably be designed to keep the patient securely seated in the chair, maintaining the oral cavity in the same position with respect to the head support, regardless of where the chair is adjusted to.
Finally, as with all consumer products, it is desirable to meet all the sought-after attributes of a product while keeping it easy to manufacture and inexpensive to produce and sell, giving its manufacturer a greater advantage in the marketplace.
One problem that has existed in previous patient supports has been providing easily operable means for moving an arm rest out of the way to allow easy entrance and exit. Heretofore, various camlock, pushing, pulling, and even release mechanisms for completely removing the arm support have been proposed for solving this problem. Each of the previous mechanisms has been cumbersome to operate as well as prone to accidental movement while a procedure is being performed. It is, therefore, desired to provide an arm movement mechanism that is easy to operate yet remains locked firmly in place while a procedure is being performed, preventing jerk-type reactions by the patient from releasing the arm support.
Another problem in patient supports of the prior art has been a tendency for movement of the oral cavity with respect to the head support member during adjustment of the patient support. In the past, a patient's head would typically slide downwardly along the back member, away from the optimum point of support by the headrest, while the chair was being reclined. This also tended to pull on the patient's clothing. It has surprisingly been discovered that by carefully adjusting the point of pivotal connection of the backrest to the seat member, this objectional head travel and clothing pull can be entirely eliminated, thereby allowing the dentist to position a patient's head on the headrest and then recline the patient support to an operating position without having to readjust the headrest. It is far easier to adjust a headrest when the chair is up in a seated position and the weight of a patient is not concentrated downward on the headrest than it is to make such adjustments once the chair has been reclined.
Another problem that has remained unsolved until the present invention was a failure to recognize the impact on patient support and comfort from the shifting of the center of gravity of the human body when traveling from a seated to a reclined position. Namely, when in a seated position, the majority of the body's weight is oriented downwardly along a line extending from the shoulders toward the bottom of the buttocks. When reclined, however, the force of gravity tends to pull downwardly along the line extending from the front of the chest to the back. Patient supports in the past have operated by elevating the legs, often about a pivotal connection near the knees, in order to make the patient more comfortable when reclining. Fixed-knee patient supports have not accommodated for the change of gravitational pull whatsoever. It has been surprisingly discovered that a greater sense of security and a smoother ride can be accomplished by adjusting the seat angle upwardly as the back support reclines during the beginning of the reclining motion.
The advent of advanced electronic circuitry has permitted the design of patient supports with pre-programmed adjustability. In other words, it has become possible to pre-program the most desired position for beginning examination into the circuitry of a dental chair, so that a single button can be pushed on the chair in order to activate automatic reclining mechanisms to move it to that desired position. Similarly, pre-programmed return-to-exit circuitry is available. This has caused a potential for damage to the equipment in operatories which may be positioned behind or below the patient support, by the patient support crashing down on such equipment while being automatically moved. It has, in the past, been particularly difficult for an operator to reach the proper control switch quickly enough to prevent damage upon noticing that the chair is about to do damage. It is, therefore, desired to provide circuitry to halt the automatic recline or return of a dental patient support by movement of almost any of the other control switches in any of their operating directions. This would provide added safety.
Heretofore, extra heavy cushions have been required to provide a comfortable feeling to the patient, especially if contouring is desired to keep a patient centered in the seat. The bulkiness of such cushions has taken away from the aesthetic appearance of patient supports in the past, rendering them quite bulky and clumsy in appearance. It is desired to provide a patient support which remains thin and appealing to the eye while remaining comfortable to sit in and tending to keep the patient centered. It is further desired to provide integral lumbar support for patients.
Finally, replaceability of the cushions on dental chairs is a desirable feature, to allow the dentist to change decorating schemes without having to completely replace an otherwise useful chair.